Airplane control surface



.lune 15, 1948. R. J. NEM-:SAR

AIRPLANE CONTROL SURFACEl Filed May 1o, 1944 M- ms 4 Patented June 15, 1948 AIRPLANE CONTROL SURFACE Robert J. Nebcsar, Bristol, Va., assgnor to Universal Moulded Products Corporation, Bristol, Va., a corporation of Delaware Application May 10, 1944, Serial No. 534,871A

Claims. 1

This invention relates to an improvement in airplane control surfaces and, more partlcularly, to movable control surfaces, such as rudders, elevators, ailerons, flaps, and the like.

More specifically, this invention relates to an improvement in structural features which will enable the formation of control surfaces having requisite strength and rigidity under the applied load coupled with desired lightness in weight.

Heretoiore movable `control surfaces have variously comprised a frame, usually of metal, as dural, covered with either a thin metal, as dural, or fabric skin. The thin metal skin has not proved satisfactory due to the requirement for extra balance weight and to the fact that wrinkles form in the skin. The fabric covering is also unsatisfactory since rigidity cannot be obtained due to the fact that a fabric covering has a tendency to deflectA in and outv when the load is applied, with consequent variation in the contour oi" the surface and impairment of the eihciency oi' the surface. Further, the fabric cannot take any great pressure differential which may arise on the inside and outside of the covering, thus frequently resulting in tearing the fabric away from the frame.

While a good many different constructions were made in wood more or less improving the characteristics as against the metal ones mentioned above, the main objection to use of these was the fact that due to their construction, under different atmospheric conditions, a deformation and twisting would result at the aft ribs or their trailing edges which the construction according to this invention would remedy.

Now in accordance with this invention generally, a structure is provided which comprises a frame of novel construction and a covering or skin composed of plywood applied to and secured to the frame, all as will appear from the following description with reference to the accompanying drawings, which illustrate an embodiment of the invention and in which:

Figure i is a plan View or the uncovered frame structure of a controlsurface, as a rudder.

Figure 2 is a sectional View on line 2 2, Figure 1.

Figure 3 is a sectional View taken at right angles to that of Figure 2.

Figure 4 is a sectional View on line #fl-4, Figure 3, showing av detail of construction.

Figure 5 is a sectional View showing a detail of construction.

In the several figures, l, I indicate spars extending spanwise of the structure and to which` are attached nose ribs 2, 2 and trailing edge ribs 3, 3. The spars are spaced by means of spacer members 9, Sand the nose and trailing edge ribs are spaced by spacer members d. The trailing edge ribs 3, 3 are spaced and stiiened also by spacer members d, which extend from the spars to adjacent the trailing edge. The spars are secured together by means of angles 5, 5 overlying the spacers il and Il and secured to the ribs 2 and 3 and spars I.

Extending lengthwise of the spars and recessed into the spars and ribs 2, 2 and 3, 3 are apron strips G, t, scallopedbetween the rib stations.

The nose skin 1 is .composed of plywood material and extends over the apron strip t to abut with the main skin sections 8, 8, also composed of plywood, just above the spars. The apron strips 5, are formed from plywood of approximately the same type and thickness asv that of the nose skin and are molded to the nose skin.k

At the trailing edge of 'the structure a trailing edge strip l0, composed of plywood and scalloped between rib stations is secured in slots formed by recessing the trailing end portions of the ribs 3, 3, respectively. The grain direction of the face plies of the trailing edge strip runs in a chordwise direction.

Secured on opposite sides of the trailing edge strip and extending spanwise are strips of wood H, l l having their grain direction running spanwise and machinedy to triangular or wedge shape, as shown in Figures 2 and 4.

The skin sections il, 8 of plywood are applied over the ribs 3, 3, abutted with the nose skin l in the plane of the spars l, I and secured by gluing to the apron strip 6, the ribs 3,3 andto the wedge shaped strip I l, I l carried by the trailing edge strip iii, which in turn is glued to the ribs 3, 3.

It will now be appreciated that in the construction according to this invention the ribs. and spars, which may be formed of wood, are secured together by the usual angles and, in addition thereto, .by the. plywood apron strips t, (i, to which the plywood nose skiny l is` molded, and which are recessed into the spars and ribs, to which they are secured by gluing. The main skin ,sectionsli 8 are butted into the nose skin'l just over the spars and are secured to the apron strip. by gluing.

Finally, the trailing edge is formed by the trailing edge strip Ill, composed of plywood the grain direction of the face plies of which runs chordwise, which extends into slots in the ribs, to which tain them in spaced relation from end to end of the Eframe, an apron strip connected to the outer face of each spar and extending a substantial distance beyond each side thereof, a pluralityr of spaced nose ribs on each side of the frame abutting one face of the spar, a plurality of spaced trailing edge ribs on each side of the frame abutting the opposite face of the spar in the same planes as the nose ribs, the ribs on one side ofl the frame being opposite those on the other side of the `frame, each rib being recessed for the reception of the apron strip on that side of the frame, and transverse spacer mem-bers normal to the rst spacer member connected to the rst spacer member and ribs on the opposite sides of the frame.

12. A control surface frame for airplanes, comprising spaced parallel spars extending substantially the full length of the frame on opposite sides thereof, -a spacer member secured to one side of each of the spars and arranged to maintain them in spaced relation from end to end of the frame, an apron strip connected to the outer face of each spar and extending a substantial distance beyond each side thereof, a plurality of spaced nose ribs on each side of the frame abutting one face of the spar, :a plurality of spaced trailing edge ribs on each side of the frame abutting the opposite face of the spar in the same plane as the nose ribs, the ribs on one side of the frame being opposite those on the other side of the lframey each rib being recessed for the reception of the apron strip on that side of the frame, and four transverse spacer members normal to the rst spacer' member connected to the rst spacer member and ribs on the opposite side of the frame.

13. A control surface frame for airplanes, comprising spaced parallel spars extending substantially the full length of the frame on opposite sides thereof, a spacer member secured to a side of each of the spars and arranged to maintain them in spaced relation 'from end to end, an apron strip connected to the outer face of each spar, a plurality of spaced nose ribs on each side of the frame abutting the spars, a plurality of spaced trailing edge ribs on each side of the frame abutting the spars, in the same planes as the nose ribs, the ribs on one side of the frame being opposite those on the other side of the frame, each rib being recessed for the reception of the apron strip on that side of the frame, spacer members normal to the rst spacer mem- Iber connected to the rst spacer member and ribs on the opposite sides of the frame and four transverse angles at the junctions of the ribs land spars extending from one side of the frame to the other, each angle being secured to one of the first mentioned spacer and a transverse spacer, and extending from one apron strip to the other.

14. A control surface frame for airplanes, comprising spaced parallel spars extending substantially the full length of the frame on opposite sides thereof, a spacer member secured to one side of each of the spars and arranged to maintain them in spaced relation from endto end, an apron strip connected to the outer `face of each spar, a plurality of spaced nose ribs on each side of the frame abutting the spars, a plurality of spaced trailing edge ribs on each side of the frame abutting the spars, in the same planes as the nose ribs, the ribs on one side of the frame being opposite those on the other side of the frame, each rib being recessed for the reception of the apron strip on that side of the frame, and four transverse spacer members normal to the first spacer member connected to the rst spacer member` 4and ribs on the opposite sides of the frame, the trailing ends of the trailing edge ribs on opposite sides of the rframe being brought together and secured to a trailing edge strip.

15. A control surface frame for airplanes, comprising spaced parallel spars extending substantially the full length of the frame on opposite sides thereof, a spacer member secured to one side of each of the spars and arranged to maintain them in spaced relation from end to end, an apron strip connected to the outer face of each spar, a plurality of spaced nose ribs on each side of the frame abutting the spars, a plurality of spaced trailing edge ribs on each side 0f the frame abutting the spars in the same planes as the nose ribs, the ribs on one side of the frame being opposite those on the other side of the frame, each rib being recessed for the reception of the apron strip on that side of the frame7 and four transverse spacer members normal to the rst spacer member connected to the first spacer member and ribs on the opposite sides of the frame, the trailing ends of the trailing edge ribs on opposite sides of the frame being brought together and secured to a trailing edge strip, at least one of said last mentioned transverse spacer members connecting the trailer edge ribs on opposites of the frame to each other extending to a point adjacent to the trailing edge strip.

ROBERT J. NEBESAR.

REFERENCES CITED The following references are of record in the 

